Add abs function to OCaml backend, following aa702f2 (rehabilitate abs function in backends, 2022-11-22)

Author: mdurero

examples/ocaml/mvalue.ml

@@ -141,6 +141,10 @@ let m_floor (x : m_value) : m_value =
   if x.undefined then m_undef
   else { undefined = false; value = floor (x.value +. 0.000001) }
 
+let m_abs (x : m_value) : m_value =
+  if x.undefined then m_undef
+  else { undefined = false; value = abs_float x.value }
+
 let m_present (x : m_value) : m_value = if x.undefined then m_zero else m_one
 
 let m_multimax (bound_variable : m_value) (variable_array : m_array)

src/mlang/backend_compilers/bir_to_ocaml.ml

@@ -71,6 +71,9 @@ let rec generate_ocaml_expr (e : Bir.expression Pos.marked) :
   | FunctionCall (InfFunc, [ arg ]) ->
       let s, local = generate_ocaml_expr arg in
       (Format.asprintf "(m_floor %s)" s, local)
+  | FunctionCall (AbsFunc, [ arg ]) ->
+      let se, s = generate_ocaml_expr arg in
+      (Format.asprintf "(m_abs %s)" se, s)
   | FunctionCall (MaxFunc, [ e1; e2 ]) ->
       let s1, local1 = generate_ocaml_expr e1 in
       let s2, local2 = generate_ocaml_expr e2 in